Especially for treatment machines in the form of labeling machines, it is known to design the labeling stations or labeling units as quickly and easily exchangeable labeling modules that can be coupled to at least one operating position of the treatment machine or to its machine base or decoupled from that base to enable quick and easy adaptation of such a labeling machine of modular construction to the particular changed labeling tasks. For this purpose, it is usual to set the particular labeling module, after docking, for the labeling task to be performed with this module, such as for treating special labels etc. and, after completion of this labeling task, to decouple it from the labeling machine and to park it outside or to the side of the labeling machine until a subsequent use so that a labeling module set for another labeling task can be coupled to the operating position concerned.
The setting of the particular labeling module for its labeling task is usually performed during a setting mode or trial run of the labeling machine during which the labels applied to the packaging means are visually checked and any readjustment of the module concerned or the local labeling unit relative to the labeling machine or the packaging means moved past the labeling unit is performed until the module or the local labeling unit has the target position necessary for optimum application of the labels.
In order to achieve an alignment of these modules as early as the docking of the labeling modules to the labeling machine, it is usual to provide interacting mechanical docking-and-centering elements at the labeling modules and at the labeling machine or at the machine base. However, practice has shown that, despite the use of such elements, the high repeat or positional accuracies required for optimum labeling, e.g. few tenths of a millimeter, cannot be achieved during re-docking even of a labeling module already set and that, instead, deviations from the target position exist after re-docking. Even small positional deviations from the target position lead to a clear deterioration of the labeling quality.
For this reason, it has so far been necessary, after every re-docking of a labeling module, to re-set the module, for example in a trial run or setting mode of the labeling machine. This is a time-consuming procedure.